Washing machine and method of controlling the same

ABSTRACT

A washing machine which prevents wash water in a plurality of tubs from being simultaneously drained, and a method of controlling the washing machine. The washing machine includes a plurality of tubs, a plurality of drain devices to discharge wash water in the plurality of tubs to the outside, and a control device connected to the plurality of tubs to selectively drain the wash water in the plurality of tubs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.2009-0038562, filed on Apr. 30, 2009 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

Embodiments relate to a drain structure of a washing machine with aplurality of tubs, in which laundries are divisionally washed accordingto volumes and kinds of laundry, and a method of controlling drainage ofthe washing machine.

2. Description of the Related Art

In general, washing machines (usually, drum washing machines) areapparatuses which include one tub and wash contaminated laundry usingwater and a detergent. Each washing machine performs washing of laundrythrough a series of cycles including a wash cycle, in which laundry isput into a tub and contaminants are removed from the laundry using watercontaining a detergent (specifically, wash water), a rinse cycle, inwhich foam and the remainder of the detergent are removed from thelaundry using water not containing the detergent (specifically, rinsewater), a drain cycle, in which the wash water is drained, and aspin-dry cycle, in which the laundry is dehydrated through spinning at ahigh speed.

However, laundries may not be put into one tub due to difference inkinds or materials of the laundries. In a washing machine including onetub, the laundries must be divided and thus the divided laundries mustbe washed separately. In this case, since the separate washing causesinconvenience and the washing machine needs to be operated several times(for example, twice), time and energy waste is severe. Further, in acase where a small amount of laundry needs to be washed, a washingmachine having a large-capacity tub causes unnecessary power waste dueto the driving of the large-capacity tub.

Recently, as purchasing power is increased, individuals may purchase twowashing machines, i.e., a large-capacity washing machine and asmall-capacity washing machine, in order to solve the above problem.However, when the two washing machines simultaneously perform drain orspin-dry cycles respectively, wash water may overflow a sewer due to alimited sewerage capacity of a mounting space.

Further, since each washing machine requires a drain device,manufacturing expenses are increased, and drain cycles of the twowashing machines cannot be articulately controlled.

Moreover, in a case where a conventional washing machine includes aplurality of tubs, a structure of a drain device of the washing machinehas not been disclosed.

SUMMARY

Therefore, it is one aspect to provide a washing machine, which preventswash water in a plurality of tubs from being simultaneously drained, anda method of controlling the washing machine.

It is a further aspect to provide a washing machine, in which drainageof a plurality of tubs is selectively carried out, and a method ofcontrolling the washing machine.

It is another aspect to provide a washing machine having a plurality oftubs, in which manufacturing expenses of a drain device are reduced, anda method of controlling the washing machine.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the embodiments.

In accordance with one aspect, a washing machine includes a plurality oftubs, a plurality of drain devices to discharge wash water in theplurality of tubs to the outside, and a control device connected to theplurality of tubs to selectively drain the wash water in the pluralityof tubs.

The plurality of tubs may include a pair of first and second tubs, andthe plurality of drain devices may include a first drain deviceconnected to the first tub, and a second drain device connected to thefirst tub and the first drain device.

The first drain device may include a first drain pipe provided with oneend communicated with the first tub and the other end extended to theoutside, and the second drain device may include a second drain pipeprovided with one end communicated with the second tub and the other endcommunicated with the first drain pipe, and a drain valve to open andclose the second drain pipe.

The first drain device may further include a drain valve to open andclose the first drain pipe.

The first drain device may further include a drain pump provideddownstream of a junction of the first drain pipe and the second drainpipe.

The other end of the second drain pipe may be extended to the outside ofthe main body, and the first drain device may further include aconnection pipe provided with one end communicated with the first drainpipe and the other end communicated with the second drain pipe.

At least one of the connection pipe and the second drain pipe mayinclude a connector to facilitate connection between the connection pipeand the second drain pipe.

The control device may be a microcomputer to selectively open and closethe first and second drain valves.

The microcomputer may close the second drain valve and open the firstdrain valve when draining the first tub.

The microcomputer may close the first drain valve and open the seconddrain valve when draining the second tub.

When instructions indicating simultaneous draining of the first andsecond tubs are input to the control device, the control device mayfirst drain any one of the first and second tubs and then drain theother one of the first and second tubs.

The control device may be an opening and closing device to selectivelyopen and close the first and second drain pipes by flows of wash waterin the first and second drain pipes.

The opening and closing device may include an opening and closing memberprovided to be rotatable by the flows of wash water in the first andsecond drain pipes.

The opening and closing device may further include stoppers to preventexcessive rotation of the opening and closing member.

The stoppers may include a first stopper to support the opening andclosing member, if the opening and closing member closes the first drainvalve, and a second stopper to support the opening and closing member,if the opening and closing member closes the second drain valve.

The first drain device may further include a drain pump provided in themiddle of the first drain pipe, and the opening and closing member, whenthe drain pump is driven, may be rotated by a pump pressure of the drainpump and thus open the first drain pipe and close the second drain pipe.

The second tub may be disposed above the first tub, the opening andclosing member, when only the drain valve among the drain valve and thedrain pump is driven, may be rotated by the pressure of wash water inthe second tub and thus open the second drain pipe and close the firstdrain pipe.

The plurality of tubs may include first and second tub disposed at upperand lower parts.

In accordance with a further aspect of the present invention, a washingmachine including a first tub, a second tub disposed above the firsttub, a first drain pipe to discharge wash water in the first tub to theoutside, a second drain pipe to discharge wash water in the second tubto the outside, and an opening and closing device to selectively openand close the first and second drain pipes.

The opening and closing device may close the second drain pipe whileopening the first drain pipe, and close the first drain pipe whileopening the second drain pipe.

A drain pump may be provided in the middle of the first drain pipe, anda drain valve may be provided in the middle of the second drain pipe.

The opening and closing device may be an opening and closing membermoving by pressures of wash water in the first and second drain pipes.

The opening and closing member may be rotatably connected to aconnection portion between the first and second drain pipes.

In accordance with another aspect, a washing machine includes a firsttub, a second tub disposed above the first tub, a first drain pipe todischarge wash water in the first tub to the outside, a second drainpipe to discharge wash water in the second tub to the outside, a pair ofdrain valves to respectively open and close the first and second drainpipes, and a control device to selectively open and close the pair ofdrain valves.

A junction, where the wash water in the first drain pipe and the washwater the second drain pipe are joined, may be provided, and a drainpump may be provided downstream of the junction.

The control device may close the drain valve to open and close thesecond drain pipe and drives the drain pump while opening the drainvalve to open and close the first drain pipe.

The control device may close the drain valve to open and close the firstdrain pipe while opening the drain valve to open and close the seconddrain pipe.

In accordance with another aspect, a method of controlling a washingmachine, which has a plurality of tubs, and drain devices to dischargewash water in the plurality of tubs to the outside, includes judgingwhether or not drain cycles of all the plurality of tubs are performed,and controlling the drain devices such that wash water in the pluralityof tubs is sequentially drained, when it is judged that the drain cyclesof all the plurality of tubs are performed.

The plurality of tubs may include first and second tubs, and thesequential draining of the plurality of tubs may be achieved by firstdraining any one of the first and second tubs and then draining theother one of the first and second tubs.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a perspective view illustrating the external appearance of awashing machine in accordance with one embodiment;

FIG. 2 is a longitudinal-sectional view illustrating the configurationof the washing machine in accordance with the embodiment;

FIG. 3 is a control block diagram of the washing machine in accordancewith the embodiment;

FIG. 4 is a longitudinal-sectional view illustrating the configurationof a washing machine in accordance with a further embodiment;

FIG. 5 is a longitudinal-sectional view illustrating the configurationof a washing machine in accordance with another embodiment;

FIG. 6 is a perspective view of an essential portion of the washingmachine in accordance with the embodiment;

FIGS. 7 and 8 are enlarged views illustrating the operation of thewashing machine in accordance with the embodiment during draining; and

FIG. 9 is a perspective view of an essential portion of a washingmachine in accordance with a modified embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout.

Hereinafter, one embodiment will be described in detail with referenceto the accompanying drawings.

FIG. 1 is a perspective view illustrating the external appearance of awashing machine in accordance with one embodiment, and FIG. 2 is alongitudinal-sectional view illustrating the configuration of thewashing machine in accordance with the embodiment.

As shown in FIGS. 1 and 2, the washing machine in accordance with thisembodiment includes plural (for example, two) doors 11 and 12 formed atupper and lower parts of a main body 10 forming the external appearanceof the washing machine such that laundries are divisionally put into themain body through the plural doors 11 and 12, an input unit 20 providedbetween the plural doors 11 and 12 to input user instructions regardingwashing courses and an operation of the washing machine, and a displayunit 21 to display the washing courses and the operating state of thewashing machine.

In this embodiment, the main body 10 is configured to surround first andsecond tubs 41 and 42, and the first tub 41 and the second tub 42 arecommunicated with each other in the main body 10.

The input unit 20 includes a power button, an operation/start button tostart the operation of the washing machine, a tub selection button toselect a washing tub to be used so as to perform the operation, such assimultaneous washing or independent washing, using plural (for example,two) tubs, which divisionally wash laundries, and a course and functionbutton to select washing courses and washing functions of the respectivetubs. The shape of the input unit 20 is not limited thereto, but may bevariously modified.

Further, detergent supply parts 31 and 32 to supply detergents to theplural tubs 41 and 42 are respectively provided the upper end and thecenter of the left side of the main body 10.

Although this embodiment illustrates that the detergent supply parts 31and 32 to supply detergents to the plural tubs 41 and 42 arerespectively provided, one detergent supply part 31 or 32 may beprovided so as to supply the detergents to the tubs 41 and 42 viaseparate channels. The positions of the detergent supply parts 31 and 32are not limited thereto, but the detergent supply parts 31 and 32 may belocated at any positions, where a user may easily provide the detergentsto the tubs 41 and 42 respectively.

In FIG. 2, in the washing machine in accordance with this embodiment,the plural (for example, two) tubs to divisionally wash laundriesaccording to volumes or kinds of the laundries are provided in upper andlower parts of the main body 10. That is, a first tub 41 having a largecapacity (for example, more than 10 Kg) to wash laundry having a largevolume is installed at the upper part of the main body 10, and a secondtub 42 having a smaller capacity than the first tub 41 to wash laundryhaving a small volume is installed at the lower part of the main body10.

The first and second tubs 41 and 42 may have the same capacity, ifnecessary. However, the first and second tubs 41 and 42 may be dividedinto a tub having a large capacity and a tub having a small capacityfrom the viewpoint of characteristics of the washing machine having theplural tubs 41 and 42. As stated above, the above structure of thewashing machine allows only the small-capacity second tub 42 to bedriven when a small volume of laundry is desired to be washed(particularly, through boil-washing), thereby prevent unnecessary powerwaste.

The fundamental configurations of the first and second tubs 41 and 42are the same. Cylindrical first and second drums 51 and 52 provided withmultiple holes are rotatably installed in the first and second tubs 41and 42, and a driving device to rotate first and second rotary shafts 61and 62 connected to the first and second drums 51 and 52 so as toperform the wash, rinse, and drain cycles is installed at the outersurfaces of the rear parts of the first and second tubs 41 and 42. Thedriving device includes a direct drive motor 71 to rotate the firstrotary shaft 61, a motor 72 fixed to the outer surface of the second tub42, and a driving belt 73 to transmit driving force of the motor 72 tothe second rotary shaft 62. The driving device is not limited to theabove structure, but may have a reverse structure. Further, direct drivemotors may be respectively mounted at the first and second rotary shafts61 and 62, or motors and driving belts may be respectively mounted atthe first and second rotary shafts 61 and 62. Moreover, the tubs 41 and42 may be simultaneously or independently driven by a driving methodusing a clutch.

First and second water supply devices 81 and 82 to supply water (washwater or rinse water) to the tubs 41 and 42 are respectively installedabove the first and second tubs 41 and 42. The first and second watersupply devices 81 and 82 include first and second water supply pipes 81a and 82 a connecting an external water supply pipe 80 and the first andsecond detergent supply parts 31 and 32 to supply water (wash water orrinse water) to the tubs 41 and 42, and first and second water supplyvalves 81 b and 82 b installed in the middle of the first and secondwater supply pipes 81 a and 82 a. This configuration causes watersupplied to the insides of the tubs 41 and 42 to pass through the firstand second detergent supply units 31 and 32, thereby allowing thedetergent in the first and second detergent supply units 31 and 32 to besupplied together with water to the first and second tubs 41 and 42.

Although this embodiment exemplarily discloses only the fundamentalconfiguration of the washing machine, a drying device to achieve anadditional function may be independently provided at each of the tubs.

The washing machine in accordance with this embodiment may furtherinclude first and second drain devices 100 and 110 to drain water in thefirst and second tubs 41 and 42, and a control device (hereinafter,referred to as a ‘control unit’; with reference to FIG. 3) 120electrically connected with the drain devices 100 and 110 to selectivelydrain the wash water in the first and second tubs 41 and 42 to theoutside.

The first drain device 100 includes a first drain pipe 101 provided withone end communicated with the first tub 41 and the other end extended tothe outside, and a first drain valve 102 to open and close the firstdrain pipe 101. A drain pump 103 to forcibly discharge wash water and adrain guide pipe 104 to guide the wash water discharged by the drainpump 103 to the outside may be provided at an outlet side of the firstdrain valve 102.

The second drain device 110 includes a second drain pipe 111 providedwith one end communicated with the second tub 42 and the other endextended to the first drain device 100, and a second drain valve 112 toopen and close the second drain pipe 111.

The second drain pipe 111 is extended from the second tub 42 to thefirst tub 41 through the opened upper surface of the first tub 41 andthe opened lower surface of the second tub 42 under the condition thatthe second drain pipe 111 is not exposed to the outside of the main body10.

Therefore, the second drain pipe 111 is extended to the first tub 41without being exposed to the outside, and is joined with the first drainpipe 101 between the first drain valve 102 and the drain pump 103.

After the second drain pipe 111 is joined with the first drain pipe 101,the first drain pipe 101 is connected to the drain pump 103, and thedrain pump 103 is connected to an external drain pipe 104.

FIG. 3 is a control block diagram of the washing machine in accordancewith the embodiment of the present invention. The washing machineincludes an input unit 20, a sensor unit 122, a control unit 120, and adriving unit 121.

The input unit 20 serves to input operation data, regarding a washingcourse (for example, simultaneous washing or independent washing) and awashing function of the first and second tubs 41 and 42 to be selectedso as to be used simultaneously or independently, to the control unit120.

The sensor unit 122 serves to sense water levels of the respective tubs41 and 42 and transmit the sensed water levels to the control unit 120.

The control unit 120 is a microcomputer to control the overall operationof the washing machine, such as the wash, rinse, drain, and spin-drycycles of the first and second tubs 41 and 42, according to theoperation data input through the input unit 120. If both the first andsecond tubs 41 and 42 are used to perform washing under the conditionthat times when laundries are respectively put into the first and secondtubs 41 and 42 or volumes of the laundries put into the first and secondtubs 41 and 42 and washing courses of the first and second tubs 41 and42 are different, the first and second tubs 41 and 42 perform respectivecycles according to times for the respective cycles stored in thecontrol unit 120.

While the first and second tubs 41 and 42 perform cycles through thecontrol unit 120, the drain cycle of one of the first and second tubs 41and 42 may be performed before the drain cycle of the other one of thefirst and second tubs 41 and 42 is not finished.

In this embodiment, if the drain cycles of the first and second tubs 41and 42 are simultaneously started, the drain cycle of one of the firstand second tubs 41 and 42 is performed first while holding the draincycle of the other one of the first and second tubs 41 and 42, and thenthe held drain cycle of the other one of the first and second tubs 41and 42 is performed. That is, the drain cycles of the first and secondtubs 41 and 42 are sequentially performed.

Further, if the drain cycle of one of the first and second tubs 41 and42 is started after the drain cycle of the other one of the first andsecond tubs 41 and 42 is not finished, the drain cycle of the one of thefirst and second tubs 41 and 42 is held until the first started draincycle of the other one of the first and second tubs 41 and 42 isfinished, and then the drain cycle of the one of the first and secondtubs 41 and 42 is performed after the first started drain cycle of theother one of the first and second tubs 41 and 42 is finished.

For this reason, the control unit 120 controls the first and seconddrain valves 102 and 112 and the drain pump 103 such that if the draincycle of any one of the first and second tubs 41 and 42 is performed,the drain cycle of the other one of the first and second tubs 41 and 42is not performed until the drain cycle of the one of the first andsecond tubs 41 and 42 is finished.

In this embodiment, if instructions requiring drain cycles of the firstand second tubs 41 and 42 are simultaneously input, the control unit 120opens the first drain valve 102 and closes the second drain valve 112 soas to first perform the drain cycle of the first tub 41, and then drivesthe drain pump 103. Thereafter, when it is judged that the drain cycleof the first tub 41 is completed based on a value sensed by the sensorunit 122 including water level sensors (not shown), the control unit 120closes the first drain valve 102 and opens the second drain valve 112,and then drives the drain pump 103, thereby completing the drain cycleof the second tub 42.

Further, when the second tub 42 starts its drain cycle under thecondition that the drain cycle of the first tub 41 is performed byopening the first drain valve 102 and driving the drain pump 103, thecontrol unit 120 holds the closed state of the second drain valve 112until the drain cycle of the first tub 41 is completed.

Thereafter, when the drain cycle of the first tub 41 is completed, thesensor unit 122 senses the completion of the drain cycle of the firsttub 41, and the control unit 120 closes the first drain valve 102 andopens the second drain valve 112 based on the result sensed by thesensor unit 122, thereby performing the drain cycle of the second tub42. At this time, the drain pump 103 may be driven, or the drain cycleof the second tub 42 may be performed without driving of the drain pump103 because the second tub 42 is mounted above the first tub 41.

In the same manner, when the first tub 41 starts its drain cycle underthe condition that the drain cycle of the second tub 42 is performed,the control unit 120 holds the closed state of the first drain valve 102until the drain cycle of the second tub 42 is completed.

Thereafter, when the drain cycle of the second tub 42 is completed, thecontrol unit 120 closes the second drain valve 112 and opens the firstdrain valve 102, thereby performing the drain cycle of the first tub 41.

The control unit 120 sequentially performs the drain cycles of the firstand second tubs 41 and 42 by selectively opening and closing the firstand second drain valves 102 and 112, as described above, thus preventingthe first and second tubs 41 and 42 from being simultaneously drained.

Further, the drain cycles of the first and second tubs 41 and 42 areperformed using one drain pump 103, thus simplifying a drain structureof the washing machine and reducing manufacturing expenses of thewashing machine.

Although this embodiment describes that the first and second tubs aredivisionally installed at upper and lower parts of the washing machine,the present invention is not limited thereto. That is, the first andsecond tubs may be divisionally installed at right and left parts of thewashing machine.

Hereinafter, a further embodiment will be described in detail withreference to the accompanying drawings.

A main body and drain devices in this embodiment differ from those inthe former embodiment shown in FIGS. 1 to 3, but other parts in thisembodiment may be substantially the same as those in the formerembodiment.

Hereinafter, those parts in this embodiment, which are substantially thesame as those in the former embodiment, are denoted by the samereference numerals even though they are depicted in different drawings,and a detailed description thereof will thus be omitted because it isconsidered to be unnecessary.

FIG. 4 is a longitudinal-sectional view illustrating the configurationof a washing machine in accordance with a further embodiment of thepresent invention.

In this embodiment, a main body 200 includes a first main body 210, inwhich a first tub 41 is accommodated, and a second main body 220, inwhich a second tub 42 is accommodated, provided above the first mainbody 210.

The washing machine with the first and second tubs 41 and 42 may beinstalled by stacking the second main body 220 on an upper surface 213of the first main body 210 by a user.

That is, the first main body 210 and the second main body 220 may besold separately. If a user requires plural tubs, the user purchases thefirst and second main bodies 210 and 220 simultaneously or individually,and installs the second main body 220 on the upper surface 213 of thefirst main body 210.

In this embodiment, the washing machine includes a first drain device300 provided in the first main body 210 to drain water in the first tub41, a second drain device 310 provided in the second main body 220 todrain water in the second tub 42, and a control unit 120 (with referenceto FIG. 3) electrically connected with the first and second draindevices 300 and 310 to selectively drain water in the first and secondtubs 41 and 42 to the outside.

The first drain device 300 includes a first drain pipe 301 provided withone end communicated with the first tub 41, and a first drain valve 302to open and close the first drain pipe 301. A drain pump 303 to forciblydischarge wash water and a drain guide pipe 304 to guide the wash waterdischarged by the drain pump 303 to the outside may be provided at anoutlet side of the first drain valve 302.

The first drain device 300 further includes a connection pipe 305provided with one end communicated with the first drain pipe 301 betweenthe first drain valve 302 and the drain pump 303.

The second drain device 310 includes a second drain pipe 311 providedwith one end communicated with the second tub 42 and the other endextended to the outside of the second main body 220, and a second drainvalve 312 to open and close the second drain pipe 311. The second drainpipe 311 is extended to the outside of the second main body 220 througha rear surface 225 of the second main body 220.

The connection pipe 305 guides wash water, flowing through the seconddrain pipe 311 of the second drain device 310, to the first drain device300. The other end of the connection pipe 305 is connected to aconnector 230 for connection with the second drain pipe 311, and theconnection pipe 305 is fixed to a rear surface of the first main body210.

In the above configuration, in order to selectively perform drain cyclesof the first and second tubs 41 and 42 in the same manner as the formerembodiment shown in FIGS. 1 to 3, interconnection between the firstdrain device 300 of the first main body 210 and the second drain device310 of the second main body 220 is required.

The second main body 220 is stacked on the upper surface 213 of thefirst main body 210, and the first drain device 300 and the second draindevice 310 are interconnected by connecting the end of the second drainpipe 311, extended to the outside of the second main body 220, to theconnector 230.

If the first main body 210 and the second main body 220 are stacked, asdescribed above, the control unit 120 may control the first and secondtubs 41 and 42 such that the drain cycles of the first and second tubs41 and 42 are selectively performed, in the same manner as the formerembodiment shown in FIGS. 1 to 3.

When the first and second tubs 41 and 42 perform washing of laundries,the control unit 120 controls the first and second drain valves 302 and312 and the drain pump 303 in the same manner as the former embodimentshown in FIGS. 1 to 3, and thus performs the same operation as that inthe former embodiment, thereby achieving the same effect.

Although not shown in FIG. 4, the control unit 120 (with reference toFIG. 3) is a microcomputer provided in the first main body 210, and iselectrically connected with the second drain valve 312 to control thesecond drain device 310 of the second main body 220.

Alternatively, a separate control unit to control the second tub 42 anda water supply device may be provided in the second main body 220, andthe control unit 120 in the first main body 210 may be connected to therespective parts of the second main body 220 so as to control the secondmain body 220 using the control unit 120 in the first main body 210.

Further, according to mounted spaces for the washing machine, instead ofthe stacking of the second main body 220 on the upper surface 213 of thefirst main body 210, the first and second main bodies 210 and 220 may bemounted on a level or stepped ground such that they are adjacent to eachother or are separated from each other by a designated distance, andthen the second drain pipe 311 of the second main body 220 is connectedto the connection pipe 350 of the first main body 210.

Hereinafter, another embodiment will be described in detail withreference to the accompanying drawings.

Drain devices in this embodiment differ from those in the formerembodiment shown in FIGS. 1 to 3, but other parts in this embodiment maybe substantially the same as those in the former embodiment.

Hereinafter, those parts in this embodiment, which are substantially thesame as those in the former embodiment, are denoted by the samereference numerals even though they are depicted in different drawings,and a detailed description thereof will thus be omitted because it isconsidered to be unnecessary.

FIG. 5 is a longitudinal-sectional view illustrating the configuration awashing machine in accordance with another embodiment of the presentinvention, FIG. 6 is a perspective view of an essential portion of thewashing machine in accordance with the embodiment, and FIGS. 7 and 8 areenlarged views illustrating the operation of the washing machine inaccordance with the embodiment during draining.

The washing machine in accordance with this embodiment includes firstand second drain devices 400 and 410 to drain wash water in first andsecond tubs 41 and 42, and a control device 500 mechanically connectedto the drain devices 400 and 410 to selectively drain the wash water inthe first and second tubs 41 and 42 to the outside.

The first drain device 400 includes a first drain pipe 401 provided withone end communicated with the first tub 41, and a drain pump 403 toforcibly discharge wash water and a drain guide pipe 404 to guide thewash water discharged by the drain pump 403 to the outside may beprovided at an outlet side of the first drain pipe 401.

A middle portion of the drain guide pipe 404 is located at a positionhigher than the highest level of water in the first tub 41 so as toprevent the water in the first tub 41 from being naturally drained.

If the first drain device 400 includes a drain valve (not shown) to openand close the first drain pipe 401, the height of the middle portion ofthe drain guide pipe 404 may be varied.

The second drain device 410 includes a second drain pipe 411 providedwith one end communicated with the second tub 42 and the other endextended to the first drain pipe 401, and a second drain valve 412 toopen and close the second drain pipe 411.

The control device 500 is an opening and closing device 500 toselectively open and close the first and second drain pipes 401 and 411.Although the opening and closing device 500 may be formed integrallywith the first and second drain pipes 401 and 411 and the drain guidepipe 404, the control device 500 in this embodiment may be formedseparately for the sake of convenience of manufacture.

The opening and closing device 500, as shown in FIGS. 6 to 8, includes afirst opening 501 connected to the first drain pipe 401 such that washwater in the first drain pipe 401 flows into the opening and closingdevice 500, a second opening 502 connected to the second drain pipe 411such that wash water in the second drain pipe 411 flows into the openingand closing device 500, and a third opening 503 connected to the drainguide pipe 404 such that the wash water flowing into the opening andclosing device 500 through one of the first and second openings 501 and502 is discharged to the drain guide pipe 404. The opening and closingdevice 500 is an approximately T-shaped or Y-shaped connection pipe.

The opening and closing device 500 includes an opening and closingmember 510 provided in an inner channel of the opening and closingdevice 500 such that the opening and closing member 510 is rotated by acurrent of wash water, and stoppers 521 and 522 to prevent excessiverotation of the opening and closing member 510.

The opening and closing member 510 is rotatably hinged to one side ofthe inner channel of the opening and closing device 500, and thestoppers 521 and 522 support the opening and closing member 510 suchthat the rotating angle of the opening and closing member 510 becomes anapproximately right angle and thus selectively opens and closes thefirst and second openings 501 and 502.

The stoppers 521 and 522 include a first stopper 521 supporting theopening and closing member 510 to prevent excessive rotation of theopening and closing member 510, if the opening and closing member 510 isrotated to a position to close the first opening 501, and a secondstopper 522 supporting the opening and closing member 510 to preventexcessive rotation of the opening and closing member 510, if the openingand closing member 510 is rotated to a position to close the secondopening 502.

Therefore, the opening and closing member 510 is rotated by a current ofthe wash water flowing through the first opening 501 or the secondopening 502, and thus selectively opens and closes the first and secondopenings 501 and 502.

Hereinafter, an operation of the drain devices of the washing machine inaccordance with this embodiment will be described.

If only the drain cycle of the first tub 41 is performed, the controlunit 120 drives the drain pump 403 under the condition that the seconddrain valve 412 is closed. Then, as shown in FIG. 8, a current of washwater flowing through the first drain pipe 401 is fed into the openingand closing device 5000 through the first opening 501 by the force ofthe drain pump 403, and the fed current of wash water rotates theopening and closing member 510 upward and the opening and closing member510 is located at a position to close the second opening 502 and openthe third opening 503. Thereby, the first tub 41 is smoothly drained.

Further, if only the drain cycle of the second tub 42 is performed, thecontrol unit 120 opens the second drain valve 412 under the conditionthat the drain pump 403 is switched off. Then, a current of wash waterflowing through the second drain pipe 411 is fed into the opening andclosing device 500 through the second opening 502, and the fed currentof wash water rotates the opening and closing member 510 toward thefirst opening 501 and the opening and closing member 510 is located at aposition to close the first opening 501 and open the second opening 502.Thereby, the second tub 42 is smoothly drained.

Moreover, in order to simultaneously perform the drain cycles of thefirst and second tubs 41 and 42, the control unit 120 may drive thedrain pump 403 and open the second drain valve 412 simultaneously.Further, in order to perform the drain cycle of the second tub 42 whileperforming the drain cycle of the first tub 41, the control unit maydrive the drain pump 403 and then open the second drain valve 412sequentially.

In this case, since the pressure generated by the drain pump 403 isgreater than the water pressure in the second tub 42, the opening andclosing member 510 closes the second opening 502 and opens the firstopening 501, and thus the drain cycle of the first tub 41 is performedfirst.

Thereafter, when the drain cycle of the first tub 41 is completed, theopening and closing member 510 is rotated to a position to close thefirst opening 501 and open the second opening 502 by the water pressurein the second tub 42, and thus the drain cycle of the second tub 42 isperformed.

Further, when the drain cycle of the first tub 41 is completed, thesensor unit 122 may sense the completion of the drain cycle of the firsttub 41, and the control unit 120 may switch off the drain pump 403 basedon the result sensed by the sensor unit 122 and then perform the draincycle of the second tub 42.

In order to require the drain cycles of both the first and second tubs41 and 42, the drain cycle of the first tub 41 located at the lower partis performed first, and then the drain cycle of the second tub 42located at the upper part is performed.

Hereinafter, a modified embodiment will be described in detail withreference to the accompanying drawings.

FIG. 9 is a perspective view of an essential portion of a washingmachine in accordance with a modified embodiment.

In the modified embodiment, a first drain valve 402 is provided in themiddle of a first drain pipe 401 and thus a drain pump is omitted,differing from the former embodiment shown in FIGS. 5 to 8. Further, adrain guide pipe 404 is extended to the outside at a position lower thanthe lower surface of the first tub 41.

In the above configuration, if only the drain cycle of the first tub 41is performed, the control unit 120 opens the first drain valve 402 underthe condition that the second drain valve 412 is closed.

A current of wash water flowing through the first drain pipe 401 is fedinto the opening and closing device 500 through the first opening 501,and the fed current of wash water rotates the opening and closing member510 upward and thus the opening and closing member 510 is located at aposition to close the second opening 502 and open the third opening 503.Thereby, the first tub 41 is smoothly drained.

Further, if only the drain cycle of the second tub 42 is performed, thecontrol unit 120 closes the first drain valve 402 and opens the seconddrain valve 412. Then, a current of wash water flowing through thesecond drain pipe 411 is fed into the opening and closing device 500through the second opening 502, and the fed current of wash waterrotates the opening and closing member 510 toward the first opening 501and the opening and closing member 510 is located at a position to closethe first opening 501 and open the second opening 502. Thereby, thesecond tub 42 is smoothly drained.

Moreover, in order to simultaneously perform the drain cycles of thefirst and second tubs 41 and 42, the control unit 120 may open the firstand second drain valves 402 and 412 simultaneously. Further, in order toperform the drain cycle of the second tub 42 while performing the draincycle of the first tub 41, the control unit may open the first drainvalve 402 and the second drain valve 412 sequentially.

Since the second tub 42 is located above the first tub 41, wash water inthe second tub 42 has a relatively high water pressure compared withwash water in the first tub 41.

Therefore, the current of wash water flowing through the second drainpipe 411 has a high pressure compared with the current of wash waterthrough the first drain pipe 401, and thus the opening and closingmember 510 is rotated in a direction of closing the first opening 501,thereby draining only the wash water in the second tub 42. When thedrain cycle of the second tub 42 is completed, the opening and closingmember 510 is rotated in a direction of closing the second opening 502by the pressure of the current of wash water in the first tub 41,thereby draining the wash water in the first tub 41.

Further, in order to perform the drain cycle of the first tub 41 whileperforming the drain cycle of the second tub 42, the control unit opensthe first drain valve 402 after opening the second drain valve 412. Atthis time, although wash water flows to the opening and closing device500 through the first drain pipe 401, since the pressure of the currentof the wash water through the second drain pipe 411 is higher, theopening and closing member 510 maintains a state of closing the firstopening 501 and opening the second opening 502. Thereafter, when thedrain cycle of the second tub 42 is completed, the opening and closingmember 510 is rotated in a direction of opening the first opening 501 bythe pressure of the current of wash water of the first tub 41. Thereby,the drain cycles of the first and second tubs 41 and 42 are completed.

By selectively draining the first and second tubs 41 and 42 using theabove opening and closing member 510, the drain cycles of the first andsecond tubs 41 and 42 may be selectively performed using only themechanical configuration of the washing machine without a separatecontrol unit to selectively perform the drain cycles of the first andsecond tubs 41 and 42.

Although a few embodiments have been shown and described, it would beappreciated by those skilled in the art that changes may be made inthese embodiments without departing from the principles and spirit ofthe invention, the scope of which is defined in the claims and theirequivalents.

1. A washing machine comprising: a plurality of tubs; a plurality ofdrain devices to discharge wash water in the plurality of tubs to theoutside; and a control device connected to the plurality of tubs toselectively drain the wash water in the plurality of tubs.
 2. Thewashing machine according to claim 1, wherein: the plurality of tubsincludes a first tub and a second tub; and the plurality of draindevices includes a first drain device connected to the first tub, and asecond drain device connected to the first tub and the first draindevice.
 3. The washing machine according to claim 2, wherein: the firstdrain device includes a first drain pipe provided with one endcommunicated with the first tub and the other end extended to theoutside; and the second drain device includes a second drain pipeprovided with one end communicated with the second tub and the other endcommunicated with the first drain pipe, and a drain valve to open andclose the second drain pipe.
 4. The washing machine according to claim3, wherein the first drain device further includes a drain valve to openand close the first drain pipe.
 5. The washing machine according toclaim 3, wherein the first drain device further includes a drain pumpprovided downstream of a junction of the first drain pipe and the seconddrain pipe.
 6. The washing machine according to claim 3, wherein: theother end of the second drain pipe is extended to the outside of themain body; and the first drain device further includes a connection pipeprovided with one end communicated with the first drain pipe and theother end communicated with the second drain pipe.
 7. The washingmachine according to claim 6, wherein at least one of the connectionpipe and the second drain pipe includes a connector to facilitateconnection between the connection pipe and the second drain pipe.
 8. Thewashing machine according to claim 4, wherein the control device is amicrocomputer to selectively open and close the first and second drainvalves.
 9. The washing machine according to claim 8, wherein themicrocomputer closes the second drain valve and opens the first drainvalve when draining the first tub.
 10. The washing machine according toclaim 8, wherein the microcomputer closes the first drain valve andopens the second drain valve when draining the second tub.
 11. Thewashing machine according to claim 2, wherein, when instructionsindicating simultaneous draining of the first and second tubs are inputto the control device, the control device first drains any one of thefirst and second tubs and then drains the other one of the first andsecond tubs.
 12. The washing machine according to claim 3, wherein thecontrol device is an opening and closing device to selectively open andclose the first and second drain pipes by flows of wash water in thefirst and second drain pipes.
 13. The washing machine according to claim12, wherein the opening and closing device includes an opening andclosing member provided to be rotatable by the flows of wash water inthe first and second drain pipes.
 14. The washing machine according toclaim 13, wherein the opening and closing device further includesstoppers to prevent excessive rotation of the opening and closingmember.
 15. The washing machine according to claim 14, wherein thestoppers include a first stopper to support the opening and closingmember, if the opening and closing member closes the first drain valve,and a second stopper to support the opening and closing member, if theopening and closing member closes the second drain valve.
 16. Thewashing machine according to claim 13, wherein: the first drain devicefurther includes a drain pump provided in the middle of the first drainpipe; and the opening and closing member, when the drain pump is driven,is rotated by a pump pressure of the drain pump and thus opens the firstdrain pipe and closes the second drain pipe.
 17. The washing machineaccording to claim 16, wherein: the second tub is disposed above thefirst tub; and the opening and closing member, when only the drain valveamong the drain valve and the drain pump is driven, is rotated by thepressure of wash water in the second tub and thus opens the second drainpipe and closes the first drain pipe.
 18. The washing machine accordingto claim 1, wherein the plurality of tubs includes a first tub and asecond tub disposed at upper and lower parts of the washing machine,respectively.
 19. A washing machine comprising: a first tub; a secondtub disposed above the first tub; a first drain pipe to discharge washwater in the first tub to the outside; a second drain pipe to dischargewash water in the second tub to the outside; and an opening and closingdevice to selectively open and close the first and second drain pipes.20. The washing machine according to claim 19, wherein the opening andclosing device closes the second drain pipe while opening the firstdrain pipe, and closes the first drain pipe while opening the seconddrain pipe.
 21. The washing machine according to claim 19, furthercomprising: a drain pump provided in the middle of the first drain pipe;and a drain valve provided in the middle of the second drain pipe. 22.The washing machine according to claim 19, wherein the opening andclosing device is an opening and closing member moving by pressures ofwash water in the first and second drain pipes.
 23. The washing machineaccording to claim 22, wherein the opening and closing member isrotatably connected to a connection portion between the first and seconddrain pipes.
 24. A washing machine comprising: a first tub; a second tubdisposed above the first tub; a first drain pipe to discharge wash waterin the first tub to the outside; a second drain pipe to discharge washwater in the second tub to the outside; a pair of drain valves torespectively open and close the first and second drain pipes; and acontrol device to selectively open and close the pair of drain valves.25. The washing machine according to claim 24, further comprising: ajunction provided where the wash water in the first drain pipe and thewash water the second drain pipe are joined; and a drain pump provideddownstream of the junction.
 26. The washing machine according to claim25, wherein the control device closes the drain valve to open and closethe second drain pipe and drives the drain pump while opening the drainvalve to open and close the first drain pipe.
 27. The washing machineaccording to claim 25, wherein the control device closes the drain valveto open and close the first drain pipe while opening the drain valve toopen and close the second drain pipe.
 28. A method of controlling awashing machine, which has a plurality of tubs, and drain devices todischarge wash water in the plurality of tubs to the outside,comprising: judging whether or not drain cycles of all the plurality oftubs are performed; and controlling the drain devices such that washwater in the plurality of tubs is sequentially drained, when it isjudged that the drain cycles of all the plurality of tubs are performed.29. The method according to claim 28, wherein: the plurality of tubsincludes first and second tubs; and the sequential draining of theplurality of tubs is achieved by first draining any one of the first andsecond tubs and then draining the other one of the first and secondtubs.